A molded product composed of polyolefin such as polypropylene or polyethylene is used often after coating the surface thereof with a coating material to improve the appearance, durability or the like. However, the polyolefin is poor in polarity and is thus inferior in adhesion to a coating material to cause a problem of easy peel of the coating film.
It is known that a coating material containing a conjugated diene polymer-cyclized product, such as polyisoprene, adheres well to polyolefin (Patent Document 1). Further, for improving the adhesion, it is proposed to use a modified conjugated diene polymer-cyclized product obtained by adding maleic anhydride to a low-molecular-weight conjugated diene polymer having the amount of cis-1,4-bond of 70% or more, and then subjecting the addition product to cyclization reaction (Patent Document 2).
The conjugated diene polymer-cyclized product described above can be used to prepare a coating material whose adhesion to a polyolefin molded product is improved to a certain extent, but the degree of improvement is not sufficient.
On one hand, a film composed of polyolefin such as polypropylene or polyethylene is relatively inexpensive and is thus widely used in various applications, and particularly in the field of food wrapping film, such film is often used as a multilayer film laminated with layers of polar polymers such as polyamide and an ethylene-vinylalcohol copolymer, for the purpose of improving resistance to oils and greases and gas permeability. However, it is difficult to adhere a nonpolar polymer and a polar polymer each other, and thus an adhesive layer for improving the adhesion between the polymers is usually arranged as an intermediate layer.
For example, Patent Document 3 proposes use of an adhesive composition comprising a chlorinated polypropylene with a chlorine content of 35% by weight or less, a styrene-butadiene-styrene block copolymer and/or a styrene-ethylene-butylene-styrene block copolymer, and a terpene resin and/or an alicyclic hydrocarbon resin.
Patent Document 4 proposes an adhesive composition comprising an acid adduct of polyethylene obtained by using a metallocene catalyst and an ethylene-vinyl acetate copolymer and/or an ethylene-alkyl acrylate.
However, even if the adhesive composition described above is used, the adhesion between a nonpolar polymer and a polar polymer is insufficient, or sufficient adhesion may not be exhibited depending on the combination of polymers.
Because qualities of foods, drinks, pharmaceutical preparations or the like are deteriorated by oxygen, they should be stored in the absence of oxygen or under conditions where oxygen is scarcely present.
Accordingly, the charging of containers or packs for storing foods, drinks, pharmaceutical preparations or the like with nitrogen is also conducted, but has a problem of increased costs in production and a problem that the containers or packs, once opened, allow air to flow therein thus failing to prevent deterioration of qualities after opening. Accordingly, various attempts at removing oxygen from a system by absorbing oxygen remaining in a container or a pack have been examined.
As the method of removing oxygen from a container or a pack, a method arranging a separated small bag containing oxygen scavenger comprising an iron powder as a main ingredient is conventionally widely used. This method is inexpensive and attains a high rate of absorption of oxygen, but there arise inconveniences when a metal detector is used for detecting a foreign body or when a container or pack containing the oxygen scavenger bag is heated without opening in a microwave oven.
Accordingly, a container or packaging material made of resin is examined to confer oxygen absorbing properties on the container or packaging material itself.
For example, use of an oxygen scavenger comprising polyterpene such as poly(α-pinene), poly(β-pinene), poly(dipentene) or the like and a transition metal salt such as cobalt neodecanoate, cobalt oleate or the like acting as an oxygen absorption catalyst, is proposed (Patent Document 7).
It is also proposed to use an oxygen scavenger comprising a conjugated diene polymer such as polyisoprene, 1,2-polybutadiene or the like and a transition metal salt (Patent Document 8).
It is further proposed to use an oxygen scavenger comprising a copolymer made of ethylene and cyclopentene, and a transition metal salt (Patent Document 9).
However, application of these conventional oxygen scavengers is sometimes difficult depending on uses because as the oxygen absorption reaction proceeds, the polymers can be deteriorated to lower mechanical strength significantly or elute the transition metal salts.    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 51-12827    Patent Document 2: JP-A No. 57-145103    Patent Document 3: Japanese Patent Application Publication No. 6-94207    Patent Document 4: Japanese Patent Application National Publication (Laid-Open) No. 2002-501108    Patent Document 5: JP-A No. 2003-192725    Patent Document 6: JP-A No. 2003-231211    Patent Document 7: Japanese Patent Application National Publication (Laid-Open) No. 2001-507045    Patent Document 8: JP-A No. 2003-71992    Patent Document 9: Japanese Patent Application National Publication (Laid-Open) No. 2003-504042